ROLLER CHAIN

ROLLER CHAIN

        The chain drive is the most commonly used medium for transmission of mechanical power. There are actually two types of links alternating in the bush roller chain. The first type is inner links, having two inner plates held together by two sleeves or bushings upon which rotate two rollers. Inner links alternate with the second type, the outer links, consisting of two outer plates held together by pins passing through the bushings of the inner links. The “bushing less” roller chain is similar in operation through not in construction; instead of separate bushings or sleeves holding the inner plates together, the plate has a tube stamped into it protruding from the hole which serves the same purpose. This has the advantage of removing one step in assembly of the chain.

Chains are part of the drive train to transmit the motor power to the black wheel. While properly lubricated chains can reach an efficiency 0f 98% or greater in the transmission, non-lubricated chains will significantly decrease performance and increase chain and sprockets wear.

Roller chains are used in low-to mid-speed drives at around 600-800 feet per minute; however, at higher speeds, around 2,000 to 3,000 feet per minute. This system allowed for a great deal of vertical axle movement, and was simpler to design and build than a rigid driveshaft in a workablea suspension. Also, it had less unstrung weight at the rear wheels than the Hotchkiss drive, which would have had the weight of the driven shaft and differential to carry as well. This meant that the vehicle would have a smoother side. The lighter unstrung mass would allow the suspension to react to bumps more effectively.

One problem with the Roller Chains is the variation in speed, or surging, caused by the acceleration and deceleration of the chain as it goes around the sprocket link by link. It starts as soon as the pitch line of the chain contacts the first tooth of the sprocket. This contact occurs at the point below the pitch circle of the sprocket. As the sprocket rotates, the chain is raised up to the pitch circle and is then dropped down again as sprocket rotation continues. Because of the fixed pitch length, the pitch line of the link cuts across the chord between two pitch points on the sprocket, remaining in this position relative to the sprocket until the link exists the sprocket. This rising and falling of the pitch line is what causes chordal effect or speed variation.